Rotary jar



Oct. 14, 1930. FENTRESS 1,778,252

ROTARY JAR Filed Feb. 14, 1928 GEORGE E FENWESS INVE TOR ATTORNEYnecessary.

Patented Oct. 14, 1930 PATENT OFFICE GEORGE E. FENTBES S, OF LOSANGELES, CALIFORNIA ROTARY JAR Application filed February 14, 1928.Serial No. 254,280.

My invention relates to the art of rotary drilling with especialreference to certain improvements in rotary jars.

In oil well drilling and particularly at excessive depths, tools andpipe are liable to become stuck in the hole. A simple straight pull onsuch objects to the capacity of the hoisting equipment is not alwayspowerful enough to recover them. In such emergencies the operation knownas jarring is J arring consists in striking a blow, in either direction,as close to the bound place as is possible, and the purpose of the toolreferred to as a jar is to strike such blows. It is an object of myinvention 'to provide a jar which produces a steady succession of blowsand which is so designed as to be used in rotary drilling.

provide a jar which produces the desiredjarring effect by a simplerotation of the drill pipe while maintaining it under a steady up wardstrain. The peculiar advantage of such jarring is that the blow issuperimposed on a steady pull, thus greatly increasing itseffectiveness. By jarring with a steady upward pull on the pipe anyslack due, for instance, to loose connections, is absorbed bythe pull,and the force of the blow is thus transmitted without los's,'direc tlyto the part to be jarred free.

.It is a still further object of my invention to provide. a rotary jarincluding" rugged means for transmitting rotation. Experience has shownthat it is good practice to run a jar above the bit when in diflicultdrilling. Such use requires the jar adapted to transmit the fulldrilling torque.

Another object of my invention is to provide a jar which utilizes theelasticity of the drill pipe in the production of blows.

I attain theseobjects by means of the mechanism illustrated in. theaccompanying drawing in which:

Figure 1 is a sectional elevation showing the striking elements incontact.

Figure 2 is a sectional elevation showing the striking elementsseparated and about half set to deliver a blow.

Figure 3 is a section on the line 3-3 of igure 1.

Figure 4 is a section on the line 4.4 of Figure 2.

Figure 5 is F i ure 2.

- y improved jar is connected to the drill pipe by the sub 11 at itsupper end, and by the threaded pin 12 at its lower end. The jar thusbecomes a part of the drill stem. The body of this jar is composed oftwo parts, a sleeve l3 and a sub 14, the sub closing the lower end ofthe sleeve and secured thereto by the threads 15. This body isrelatively stationary during jarring, the moving part of the jar beingmandrel 16, functioning within the sleeve and joined to the top sub asection on the line 5-5 of 55 I by threads 17. The mandrel extendsentire- It is a further object of my invention to.

ly through the body of the jar, the central bore 18 permitting the usualmud circulation. 7 The means for causing the jarring blows comprisesthethread 19 on the mandrel and the mating thread 20 in the sleeve. Thesethreads are interrupted as indicated in Figure 3. An anvil 21 isprovided in the sleeve 7 anda mating hammer 22 is provided on themandrel. Hammer and anvil are in contact when thethreads are ready toengage. By

' stretched, and as the threads disengage the mandrel is forcibly jerkedupward by the elasticity of the pipe, the hammer striking the anvil agoodly blow, depending for its force'on the pipe tension, the weight ofthe hammer and the speed of rotation.

The means for transmitting rotation through my improved jar comprisesthe square 23 formed on the mandrel and the socket 24 formed on the sub14, the socket being adapted to receive said square. When drilling, themandrel is lowered until these parts engage, thus locking the jar. Whenagain required for use thefree movement of the mandrel inside the sleeveis suflicient to disengage the square 23 from the socket, permitting themandrel to be rotated without rotating the sleeve.

Mud is excluded from the interior of my improved jar by the stuffingboxes 25 and 26. A suflicient amount of lubricant is maintained insidethe jar to materially reduce the wear on the threads.

When using my present invention a bit may be jarred loose' by pulling asuitable stretch in the drill pipeby means of the calf wheel and thenrotatingthe drill pipe. The speed.of rotation and the amount of tensionare subject to control by the driller. The rotation produces asuccession of upward arring blows of great force and as the jar makesheadwaythe tension in the pipe is maintained by means of the calf wheel.

4 vInrotary jars heretofore usedit has been necessary to manuallyoperate the jar. The

driller first lowered the drill pipe, rotated it to latch the ars,pulled the desired tension in the drill pipe and finally rotated thepipe backwards to unlatch the jars,'thus allowing the elasticity of thepipe to produce the desired blow. This operation. is obviously laboriousand is also destructive to equipment. A distinct danger existsin-rotating the pipe left handed in that a tool joint might unscrew. v

My improved jar is easy on equipment and strikes a ranidsuccesslon ofblows. A long travel of the mandrel is neither necessary nor desirableto the production of a hard blow, A large wearing surface is provided toreceive the impact, and the threads can be made large enough to wear aconsiderable time. The economy of such a jar is obvious.

I claim as my invention: 1, A rotary jar comprising: an outersleeve;means at the lower end of said sleeve for connecting the same mandrellongitudinall said sleeve; means at t e upper end'oif said continuousrotation of said mandrel .relative to said sleeve in conjunction with asteady.

upward strain on said drill stem produces a continuous succession ofblows of said hammer on said anvil.

2. A rotary jar comprising: an outer sleeve; means at the lower end ofsaid sleeve for connecting the same to a drill stemya mandrellongitudinally disposed through said sleeve; means at the upper end ofsaid mandrel for connecting the same to said drill stem; a hammer onsaid mandrel within said ward strain on said drill stem. 3. A device asand for the purpose set forth inclaim 2 in which the mandrel is providedwith a polygonal section and the sleeve is provided with a socketadapted to receive said polygonal section of the mandrel, when saidmandrel -is'lowered in relation to said sleeve, in such manner thatrotation ma be transmitted through said jar at the will 0 the operator.

In witness that I claim the foregoing I have hereunto subscribed my namethis 9th day of February, 1928.

GEORGE E. FENTRESS.

to a drill stem; al disposed throughmandrel for connecting the same tosaid drill I stem; a hammer comprising a collar integral with saidmandrel and presenting an impacting flat face upwards; an anvil withinsaid sleeve adapted to receive the impact of said hammer. on its entiredownward-looking f ce; a plurality of interrupted threads on saidmandrel and mating interrupted threads on said sleeve, said threadsengaging in such downwardmanner that said hammer moves ly 1n relation tosaid anvil during the engagement of said threads, said threads being mdependent of said hammer and said anvil, the interruption of saidthreads being sufficient to permit the mandrel to longitudinalb saidsleeve and cause the 1y travel throng hammer tov strike said anvil, saidthreads,

anvil, and hammer being so arranged that

